Chapter 11: Introduction

After studying this chapter, you should be able to:

LO 11-1 Explain the relationship of cooling system maintenance to total vehicle operating costs.

LO 11-2 Identify and explain the purposes and functions of the cooling system.

LO 11-3 Identify and explain the purpose of coolant circulation patterns in diesel engines.

LO 11-4 Classify and describe the types, functions, and applications of diesel engine coolant.

LO 11-5 Describe and explain the classification, composition, and applications of various antifreeze formulations.

LO 11-6 Identify and describe the construction features, types, and applications of the diesel engine cooling components.

LO 11-7 Identify and describe the types, features, and applications of cooling fans.

LO 11-8 Outline maintenance procedures and identify tools and methods used to perform maintenance on a diesel engine cooling system.

LO 11-9 Explain the application of heavy-duty on-board diagnostics and the use of electrical actuators and electronic controls in hybridized diesel engine cooling systems.

You have started to work at a school bus fleet operation. The operation has close to 200 units from different manufacturers using a variety of diesel engines, but most are less than 10 years old. While the goal is to keep the vehicles in a good state of repair, the company rigorously seeks to limit operating costs related to maintenance. Consequently, you understand the difficulty of making any service recommendation that will be multiplied 200 times, translating into either a significant amount of money spent or saved on maintenance. As you review the buses’ service records and preventive maintenance schedules, you notice that the engine coolant has never been changed in any of the vehicles (coolant is a combination of water, antifreeze, and an additive package). When you ask about this, you hear conflicting information. Some technicians say that the buses use coolant that doesn’t need to be changed. Others say that it needs to be changed, but the company doesn’t want to spend the money on parts or labor to flush and fill the cooling system with good-quality, long-life coolant (LLC) antifreeze or on disposal costs to recycle old coolant. Regardless of the final maintenance decision concerning the coolant, you will need to make a service recommendation for coolant as part of the inspection reports you are completing. As you think about a service recommendation, consider the following:

1. What specific information should you collect about the fleet, its vehicles, and its equipment to make a recommendation to either leave the coolant in the engines; drain, flush, and refill the cooling systems; or switch to stocking a single type of antifreeze versus multiple types of antifreeze?
2. List and explain the important factors that should be taken into consideration when making a decision about the selection of antifreeze you would use if the coolant was to be replaced.
3. What risks might there be, and what kind of repairs would you anticipate, if the coolant in the engines has type I or type III antifreeze?